Re[2]: Waterborne radon

[Field@amrf-po.pmeh.uiowa.edu]

On Dec 3 Franz Schoenhofer wrote:

The factor of 1: 10 000 is very well known and we use it in our calculation.
Howard Prichard has done extensive work on that.

      In reply to Franz:
      
          In addition to Gessell, Hess and 
          Prichard, credit for formulating the
          transfer factor (which probably ranges from 1,000:1 to
          100,000:1) must also go to others such as:

          Becker and Lachajczyk  "Evaluation of waterborne radon
          impact on indoor air quality and assessment of control
          options", Research Triangle Park, NC: U.S. EPA,
          EPA-600/7-84-093. Project Summary, 1984


          Nazaroff et al. "Potable water as a source of
          airborne Rn-222 in U.S. dwellings", Health Physics
          52(3):281-289, 1987.

On December 3 Franz wrote:
I think that also other radsafers would be interested in more detailed
information about the effect of radium adsorbed on iron pipes. 10 000 pCi/l
of radon in water is something which cannot be neglected. What is the
concentration of Ra-226 in this water? Taking all the disequilibrium into
account there must be incredible concentrations of Ra-226 present both in
the water and the pipes to give rise to such deposits and to such
concentrations of Rn-222.

          In response to Franz:

    Detailed information concerning this discovery can be found in
          the publication:

          Field, RW, Fisher, EL, Valentine, RL, and Kross, BC
          American Journal of Public Health, "Radium-bearing pipe
          scale deposits:implications for national waterborne radon
          sampling methods", Volume 85(4), Pages 567-570, April 1995.


          I would be glad to send a reprint out to any radsafer
          (please request reprints directly from me without posting to
          the list)

          bill-field@uiowa.edu


          Historical radium-226 concentrations in the water supply
          for the town were approximately 93mBq/L.   One year prior to
          performing the study, the city switched to a surface water
          source with radium-226 concentrations less than 1 mBq/L.  


          HpGe detector gamma analyses of scale fragments taken from
          pipes in the homes identified several members of the
          uranium-238 decay chain

          Ra-226   > 10 Bq/g
          Rn-222 progeny  > 5 Bq/g

          Thorium-232 decay chain members Ac-228 (2 Bq/g) and Tl-208
          (850 mBq/g) were also found.

          Additional studies performed since the publication have
          shown that this waterborne radon source is rather common in
          Iowa.  The EPA proposed recommendations for sampling for
          waterborne radon-222 requires sampling at the point of entry
          into the distribution system rather than at the point of
          use.  The EPA sampling strategy would not represent actual
          consumer waterborne radon exposure in a significant number
          of Iowa municipalities.  I am very interested if other
          radsafers have noted this occurrence in their part of the
          world.  My guess is that it likely occurs where there has
          been historically high radium-226 concentrations in the
          distribution system water.

          Best Regards, Bill Field

          
          R. William Field, Ph.D.
          Coordinator, Iowa Radon/Lung Cancer Study
          Department of Preventive Medicine
          N222 Oakdale Hall
          University of Iowa
          Iowa City, Iowa 52242
          319-335-4413 (phone)
          bill-field@uiowa.edu (email)